This section introduces aspects that may help facilitate a better understanding of the disclosure. Accordingly, these statements are to be read in this light and are not to be understood as admissions about what is or is not prior art.
The field of non-contact thermal imaging is associated with a variety of applications, e.g., measuring thermal characteristics of an electronic device under test. Thermal imaging using thermoreflectance has received attention in recent years. Thermoreflectance-based imaging is dependent on the measurement of the relative change in the sample's surface reflectivity as a function of temperature. As the temperature of a sample changes, the refractive index, and therefore, the reflectivity also changes. The change in reflectivity is dependent on the Thermoreflectance Coefficient, a basic material property that is a function of the imaging system's numerical aperature, illumination wavelength, the sample material and material surface characteristics, and the ambient temperature. U.S. Pat. No. 7,173,245 to Shakouri et al., incorporated by reference in its entirety into the present disclosure, describes an example of such systems and methods.
In one method, an optical signal can be used to illuminate an electronic or optoelectronic device between un-energized and energized states without contacting the device in order to interrogate thermal behavior of the device when energized. Such thermal interrogation, however, requires knowledge of thermoreflectance coefficients for various parts of the device. While the thermoreflectance coefficient of one or more parts of the device may be known, such knowledge may be lacking for other parts of the device.
There is, therefore an unmet need for a novel method and system that can interrogate thermal behavior of an electronic or optoelectronic device with a known thermoreflectance coefficient of one or more regions but with unknown thermoreflectance coefficients of one or more other regions.